I know you must feel terrible, but if they are dog lovers and their dogs go everywhere with them they will take good care of your dog. The mother is probably dying and they had to make a hard choice and took the dog with them. Your dog is in the company of their dogs and is probably enjoying himself as part of a pack. The man was probably short and rude to you because because of the situation they are in. I understand your dreadful situation. You are wondering where you dog is and how he is doing, but you will see him soon. Be comforted in that.
If they really had this big medical problem in their family to deal with, they would be happy with his offer to come get the pup.
They at hospital, etc,,, it’d be one less thing to deal with. They are up to no good.